Control Board TransformerTime Delay Relay Igniter Pressure SwitchGas ValveBlower Assy Flameholder Assy Combustion Chamber Coil Assy Temp/ Pressure Gauge TACO Pump DHW coil (single wall) DHW coil (double wall) DHW coil Transfer Tank Transfer Tank Flameholder Assy Blower Assy TACO Pump Pressure Relief Valve Combustion Chamber Coil Assy